1 files changed, 310 insertions, 0 deletions
diff --git a/drivers/acpi/acpica/evglock.c b/drivers/acpi/acpica/evglock.c
new file mode 100644
index 000000000..0ced84ae1
--- /dev/null
+++ b/drivers/acpi/acpica/evglock.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: evglock - Global Lock support
+ *
+ * Copyright (C) 2000 - 2020, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acevents.h"
+#include "acinterp.h"
+
+#define _COMPONENT          ACPI_EVENTS
+ACPI_MODULE_NAME("evglock")
+#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
+/* Local prototypes */
+static u32 acpi_ev_global_lock_handler(void *context);
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ev_init_global_lock_handler
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Install a handler for the global lock release event
+ *
+ ******************************************************************************/
+
+acpi_status acpi_ev_init_global_lock_handler(void)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE(ev_init_global_lock_handler);
+
+	/* If Hardware Reduced flag is set, there is no global lock */
+
+	if (acpi_gbl_reduced_hardware) {
+		return_ACPI_STATUS(AE_OK);
+	}
+
+	/* Attempt installation of the global lock handler */
+
+	status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL,
+						  acpi_ev_global_lock_handler,
+						  NULL);
+
+	/*
+	 * If the global lock does not exist on this platform, the attempt to
+	 * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick).
+	 * Map to AE_OK, but mark global lock as not present. Any attempt to
+	 * actually use the global lock will be flagged with an error.
+	 */
+	acpi_gbl_global_lock_present = FALSE;
+	if (status == AE_NO_HARDWARE_RESPONSE) {
+		ACPI_ERROR((AE_INFO,
+			    "No response from Global Lock hardware, disabling lock"));
+
+		return_ACPI_STATUS(AE_OK);
+	}
+
+	status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	acpi_gbl_global_lock_pending = FALSE;
+	acpi_gbl_global_lock_present = TRUE;
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ev_remove_global_lock_handler
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Remove the handler for the Global Lock
+ *
+ ******************************************************************************/
+
+acpi_status acpi_ev_remove_global_lock_handler(void)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler);
+
+	acpi_gbl_global_lock_present = FALSE;
+	status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL,
+						 acpi_ev_global_lock_handler);
+
+	acpi_os_delete_lock(acpi_gbl_global_lock_pending_lock);
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ev_global_lock_handler
+ *
+ * PARAMETERS:  context         - From thread interface, not used
+ *
+ * RETURN:      ACPI_INTERRUPT_HANDLED
+ *
+ * DESCRIPTION: Invoked directly from the SCI handler when a global lock
+ *              release interrupt occurs. If there is actually a pending
+ *              request for the lock, signal the waiting thread.
+ *
+ ******************************************************************************/
+
+static u32 acpi_ev_global_lock_handler(void *context)
+{
+	acpi_status status;
+	acpi_cpu_flags flags;
+
+	flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
+
+	/*
+	 * If a request for the global lock is not actually pending,
+	 * we are done. This handles "spurious" global lock interrupts
+	 * which are possible (and have been seen) with bad BIOSs.
+	 */
+	if (!acpi_gbl_global_lock_pending) {
+		goto cleanup_and_exit;
+	}
+
+	/*
+	 * Send a unit to the global lock semaphore. The actual acquisition
+	 * of the global lock will be performed by the waiting thread.
+	 */
+	status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);
+	if (ACPI_FAILURE(status)) {
+		ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore"));
+	}
+
+	acpi_gbl_global_lock_pending = FALSE;
+
+cleanup_and_exit:
+
+	acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
+	return (ACPI_INTERRUPT_HANDLED);
+}
+
+/******************************************************************************
+ *
+ * FUNCTION:    acpi_ev_acquire_global_lock
+ *
+ * PARAMETERS:  timeout         - Max time to wait for the lock, in millisec.
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Attempt to gain ownership of the Global Lock.
+ *
+ * MUTEX:       Interpreter must be locked
+ *
+ * Note: The original implementation allowed multiple threads to "acquire" the
+ * Global Lock, and the OS would hold the lock until the last thread had
+ * released it. However, this could potentially starve the BIOS out of the
+ * lock, especially in the case where there is a tight handshake between the
+ * Embedded Controller driver and the BIOS. Therefore, this implementation
+ * allows only one thread to acquire the HW Global Lock at a time, and makes
+ * the global lock appear as a standard mutex on the OS side.
+ *
+ *****************************************************************************/
+
+acpi_status acpi_ev_acquire_global_lock(u16 timeout)
+{
+	acpi_cpu_flags flags;
+	acpi_status status;
+	u8 acquired = FALSE;
+
+	ACPI_FUNCTION_TRACE(ev_acquire_global_lock);
+
+	/*
+	 * Only one thread can acquire the GL at a time, the global_lock_mutex
+	 * enforces this. This interface releases the interpreter if we must wait.
+	 */
+	status =
+	    acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex.
+				      os_mutex, timeout);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	/*
+	 * Update the global lock handle and check for wraparound. The handle is
+	 * only used for the external global lock interfaces, but it is updated
+	 * here to properly handle the case where a single thread may acquire the
+	 * lock via both the AML and the acpi_acquire_global_lock interfaces. The
+	 * handle is therefore updated on the first acquire from a given thread
+	 * regardless of where the acquisition request originated.
+	 */
+	acpi_gbl_global_lock_handle++;
+	if (acpi_gbl_global_lock_handle == 0) {
+		acpi_gbl_global_lock_handle = 1;
+	}
+
+	/*
+	 * Make sure that a global lock actually exists. If not, just
+	 * treat the lock as a standard mutex.
+	 */
+	if (!acpi_gbl_global_lock_present) {
+		acpi_gbl_global_lock_acquired = TRUE;
+		return_ACPI_STATUS(AE_OK);
+	}
+
+	flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
+
+	do {
+
+		/* Attempt to acquire the actual hardware lock */
+
+		ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired);
+		if (acquired) {
+			acpi_gbl_global_lock_acquired = TRUE;
+			ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
+					  "Acquired hardware Global Lock\n"));
+			break;
+		}
+
+		/*
+		 * Did not get the lock. The pending bit was set above, and
+		 * we must now wait until we receive the global lock
+		 * released interrupt.
+		 */
+		acpi_gbl_global_lock_pending = TRUE;
+		acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
+
+		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
+				  "Waiting for hardware Global Lock\n"));
+
+		/*
+		 * Wait for handshake with the global lock interrupt handler.
+		 * This interface releases the interpreter if we must wait.
+		 */
+		status =
+		    acpi_ex_system_wait_semaphore
+		    (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);
+
+		flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
+
+	} while (ACPI_SUCCESS(status));
+
+	acpi_gbl_global_lock_pending = FALSE;
+	acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
+
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ev_release_global_lock
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Releases ownership of the Global Lock.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_ev_release_global_lock(void)
+{
+	u8 pending = FALSE;
+	acpi_status status = AE_OK;
+
+	ACPI_FUNCTION_TRACE(ev_release_global_lock);
+
+	/* Lock must be already acquired */
+
+	if (!acpi_gbl_global_lock_acquired) {
+		ACPI_WARNING((AE_INFO,
+			      "Cannot release the ACPI Global Lock, it has not been acquired"));
+		return_ACPI_STATUS(AE_NOT_ACQUIRED);
+	}
+
+	if (acpi_gbl_global_lock_present) {
+
+		/* Allow any thread to release the lock */
+
+		ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending);
+
+		/*
+		 * If the pending bit was set, we must write GBL_RLS to the control
+		 * register
+		 */
+		if (pending) {
+			status =
+			    acpi_write_bit_register
+			    (ACPI_BITREG_GLOBAL_LOCK_RELEASE,
+			     ACPI_ENABLE_EVENT);
+		}
+
+		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
+				  "Released hardware Global Lock\n"));
+	}
+
+	acpi_gbl_global_lock_acquired = FALSE;
+
+	/* Release the local GL mutex */
+
+	acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex);
+	return_ACPI_STATUS(status);
+}
+
+#endif				/* !ACPI_REDUCED_HARDWARE */